Having diarrhoea which is foul smelling. Very sudden and dark coloured. Suggest the best treatment?

Three or four times a day I have diarrhoea often foul smelling .can come v suddenly.do not always have time to reach my toilet. Very runny resulting in mess everywhere. Am nervous about going out.usually dark coloured esp. First thing in morning.am worried something wrong internally. Am 73 yrs old. Pretty healthy as rule.

A few things need to be looked at.1. Do you have any health issues such as Diabetes, Hypertension?2. Are you on any medications eg. Aspirin, antibiotics etc.3. Have you undergone any surgery in the past?4. Stool which is dark colored (does it mean blackish colored or reddish?) I would suggest you to seek an appointment with your GP and he/she may recommend certain tests including colonoscopy, Upper GI endoscopy etc. A probiotic might also be advised by the GP.Please do get yourself investigated.Take care.